[llvm] [JITLink] [test] Extend preexisting MinGW XFAILs to new tests (PR #142375)

[Lang Hames via llvm-commits]

lhames wrote:

> Yep; fwiw I noted that lli does hook up a dummy __main similarly already:

Yep. Having a no-op `__main` will probably be sufficient to get the tests passing (certainly it'll address the missing symbol error).

Ideally we'd figure out what `__main`'s role in a regular program is and emulate it (a no-op might even be the right operation in a JIT context, but if so we should verify and document that).

https://github.com/llvm/llvm-project/pull/142375